June 18 (Bloomberg) -- Microsoft Corp. unveiled its own Windows-powered tablet computer called Surface, altering its strategy of focusing on software and relying on partners to make the machines in a renewed attempt to take on Apple Inc.’s iPad.

The tablet has a 10.6-inch display and will run the new version of Microsoft’s operating system, said Chief Executive Officer Steve Ballmer at an event today at Milk Studios in Los Angeles. The device’s cover serves as a track pad and a full keyboard. Surface will be available later this year.

The world’s largest software maker is stepping up its assault on the tablet market as consumers choose the devices over laptops, weakening the personal-computer market and curbing Windows revenue. The new strategy threatens to sour Microsoft’s relationship with some PC makers, many of which have been investing to develop their own Windows 8 tablets and may not want to compete directly with Microsoft.

“It will be a substantial change to the partner ecosystem,” said Michael Cherry, an analyst at Directions on Microsoft, a market-research firm in Kirkland, Washington. “This would be a definite shake-up.”

The software maker is aiming to release Windows 8 in time for the end-of-year holidays and will have a version for x86 chips from Intel Corp. and for ones based on ARM Holdings Plc’s technology, which is also used in the iPad. The Surface tablet will be available in versions running both chip designs.

Microsoft said the Surface’s price will be announced closer to when the devices are available and will be “competitive with a comparable ARM tablet or Intel Ultrabook-class PC.”

The version for ARM will go on sale when Windows 8 is released. The Intel-based version will be available about 90 days later, Microsoft said in a statement.

The ARM version of Surface weighs less than 1.5 pounds, is 9.3 millimeters thick and has a full magnesium case, the company said at the event.